A sorption apparatus is an apparatus wherein a liquid or solid adsorption medium adsorbs a second medium (i.e. the operating medium) as vapor at a higher temperature, thereby releasing heat. During the adsorption phase, the adsorption medium adsorbs the operating medium which is transformed into vapor as it evaporates upon absorbing heat from the heat exchanger in a cooling container. During the adsorption phase, the evaporating temperatures in the cooling container are in the range of between -40.degree. to +40.degree. C.
Sorption apparatus with solid adsorption mediums, referred to as "adsorption" apparatuses, operate periodically, that is, an adsorption phase is always followed by a desorption phase wherein the operating medium (e.g. water) is again separated from the adsorption medium (e.g. zeolite). During the desorption phase, the operating medium cannot evaporate and can therefore not absorb any heat in the cooling container. Also, during the adsorption phase, the "evaporation capacity" in the cooling container is not constant since the sorption force of the adsorption medium depends on several factors; e.g. the temperature of the adsorption medium, and the given concentration of the operating medium in the adsorption medium. In order to maintain a constant evaporation capacity, or a constant evaporation temperature in the cooling container, an additional control effort is necessary with adsorption apparatus in particular.
An example of a prior art cooling container of a periodically-operating adsorption apparatus, is disclosed in German Patent Application DE-OS 35 21 484. In such apparatus, during the adsorption phase, an ice bank is built up during partial evaporation of the water operating medium in the cooling container. In the above-referenced German Patent Application, the adsorption apparatus includes in addition to the cooling container, an adsorption container with a shut off means interposed between the adsorption container and the cooling container. During the adsorption phase, the water operating medium contained in the cooling container, partially evaporates and the remaining portion freezes to form ice. A heat exchanger is also provided in the cooling container and is used for cooling beverages, for example. In connection therewith, the beverage to be cooled is stored in a supply container, and is permitted to flow through the heat exchanger and transfer its heat to the water operating medium which is present in the cooling container. In order to control the discharge temperature of the beverage, a control unit is provided to control the evaporation temperature of the water by opening and closing of the shut off means.
However, such a cooling container suffers from several significant shortcomings and drawbacks. When the control of the shut off means fails, the water operating liquid in the cooling container freezes into ice, which (due to the initiated sublimation process in the cooling container during the adsorption phase) cools down to a temperature far below 0.degree. C. Consequently, the beverage which remains in the heat exchanger during this condition, freezes and thus a continuation of the beverage tapping process is interrupted. In addition, the provided control unit and the closable shut off means are complicated and expensive elements which renders such an equipped adsorption apparatus, prohibitively expensive. Consequently, such adsorption cooling apparatus is precluded from being used in a variety of cooling applications.
Accordingly, it is a primary object of the present invention to provide a cooling container for an adsorption apparatus, which incorporates a simple, inexpensive and reliable way of allowing a liquid (such as a beverage) flowing through or remaining in the heat exchanger within the cooling container, from being cooled down below 0.degree. C. during the adsorption phase of operation.
These and other objects of the present invention will become apparent hereinafter and in the claims.